Quantum dot films utilizing multi-phase resins

ABSTRACT

Multi-phase polymer films containing quantum dots (QDs) are described herein. The films have domains of primarily hydrophobic polymer and domains of primarily hydrophilic polymer. QDs, being generally more stable within a hydrophobic matrix, are dispersed primarily within the hydrophobic domains of the films. The hydrophilic domains tend to be effective at excluding oxygen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/332,765 filed May 27, 2021, which is a continuation of U.S.application Ser. No. 15/618,863 filed Jun. 9, 2017, now issued as U.S.Pat. No. 11,335,834, which is a continuation of U.S. application Ser.No. 14/460,008 filed Aug. 14, 2014, now issued as U.S. Pat. No.9,680,068, which claims the benefit of U.S. Provisional Application No.61/865,692 filed on Aug. 8, 2013, the contents of which are herebyincorporated by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to materials comprising light emittingsemiconductor quantum dots (QDs), and more specifically, multi-phasepolymer films incorporating QDs.

BACKGROUND

Light-emitting diodes (LEDs) are becoming more important to modern daylife and it is envisaged that they will become one of the majorapplications in many forms of lighting such as automobile lights,traffic signals, general lighting, liquid crystal display (LCD)backlighting and display screens. Currently, LED devices are typicallymade from inorganic solid-state semiconductor materials. The materialused to make the LED determines the color of light produced by the LED.Each material emits light with a particular wavelength spectrum, i.e.,light having a particular mix of colors. Common materials include AlGaAs(red), AlGaInP (orange-yellow-green), and AlGaInN (green-blue).

LEDs that produce white light, which is a mixture of fundamental colors(e.g., red, green and blue) or that produce light not available usingthe usual LED semiconductor materials are needed for many applications.Currently the most usual method of color mixing to produce a requiredcolor, such as white, is to use a combination of phosphorescentmaterials that are placed on top of the solid-state LED whereby thelight from the LED (the “primary light”) is absorbed by thephosphorescent material and then re-emitted at a different frequency(the “secondary light”). The phosphorescent material “down converts” aportion of the primary light.

Current phosphorescent materials used in down-converting applicationstypically absorb UV or blue light and convert it to light having longerwavelengths, such as red or green light. A lighting device having a blueprimary light source, such as a blue-emitting LED, combined withsecondary phosphors that emit red and green light, can be used toproduce white light.

The most common phosphor materials are solid-state semiconductormaterials, such as trivalent rare-earth doped oxides or halophosphates.White emission can be obtained by blending a blue light-emitting LEDwith a green phosphor such as, SrGa₂S₄:Eu₂ ²⁺ and a red phosphor suchas, SrSi₅Ni₈:Eu₂ ²⁺ or a UV light-emitting LED plus a yellow phosphorsuch as, Sr₂P₂O₇:Eu²⁺; Mn²⁺, and a blue-green phosphor. White LEDs canalso be made by combining a blue LED with a yellow phosphor.

Several problems are associated with solid-state down-convertingphosphors. Color control and color rendering may be poor (i.e., colorrendering index (CRI)<75), resulting in light that is unpleasant undermany circumstances. Also, it is difficult to adjust the hue of emittedlight; because the characteristic color emitted by any particularphosphor is a function of the material the phosphor is made of. If asuitable material does not exist, then certain hues may simply beunavailable. There is thus a need in the art for down-convertingphosphors having greater flexibility and better color rendering thanpresently available.

BRIEF SUMMARY OF THE INVENTION

Films containing QDs are described herein. The films may be used ascomponents for LED lighting devices, particularly, as phosphor films fordown-converting light emitted from a solid-state LED semiconductormaterial.

The films are formed from two or more polymer materials, for example,two or more polymer resins. The films at least partially phase-separate,such that some domains within a film are primarily one of the polymermaterials and other domains within the film are primarily the polymermaterial. One of the polymer materials is chosen to be highly compatiblewith the QDs. Another of the polymer materials is highly effective atexcluding oxygen. As a result, the multi-domain films include QD-richdomains of QDs dispersed in the QD-compatible polymer, those domainsbeing surrounded by QD-poor domains of the oxygen-excluding polymer.Thus, the QDs are suspended in a medium with which they are highlycompatible and are protected from oxygen by the oxygen-excludingdomains.

Methods of making such films are also described herein. According tosome embodiments, QDs are suspended in a solution of a first polymerresin (i.e., a QD-compatible resin). The QD suspension is then added toa solution of the second polymer resin (the oxygen-excluding resin),yielding an emulsion. A film is formed of the emulsion, which can thenbe cured to form a solid film.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary as well as the following detailed description willbe better understood when read in conjunction with the appendeddrawings. For the purpose of illustration only, there is shown in thedrawings certain embodiments. It is understood, however, that theinventive concepts disclosed herein are not limited to the precisearrangements and instrumentalities shown in the drawings.

FIG. 1 is a schematic illustration of a prior art use of a filmcontaining QDs to down-convert light emitted by a LED.

FIG. 2 is a schematic illustration of a QD-containing polymer sandwichedbetween transparent sheets.

FIG. 3 is a schematic illustration of a two-phase film having aQD-compatible phase and an oxygen-excluding phase.

FIG. 4 is a flowchart illustrating the steps of making a two-phase film.

FIG. 5 is a plot of QD quantum yields in various films.

FIG. 6 illustrates stability studies of two-phase LMA/epoxy films.

DESCRIPTION

There has been substantial interest in exploiting the properties ofcompound semiconductor particles with dimensions on the order of 2-50nm, often referred to as quantum dots (QDs) or nanocrystals. Thesematerials are of commercial interest due to their size-tunableelectronic properties that can be exploited in many commercialapplications.

The most studied of semiconductor materials have been the chalcogenidesII-VI materials namely ZnS, ZnSe, CdS, CdSe, CdTe; especially CdSe dueto its tunability over the visible region of the spectrum. Reproduciblemethods for the large-scale production of these materials have beendeveloped from “bottom up” techniques, whereby particles are preparedatom-by-atom, i.e., from molecules to clusters to particles, using “wet”chemical procedures.

Two fundamental factors, both related to the size of the individualsemiconductor nanoparticles, are responsible for their uniqueproperties. The first is the large surface-to-volume ratio. As particlesbecome smaller, the ratio of the number of surface atoms to those in theinterior increases. This leads to the surface properties playing animportant role in the overall properties of the material. The secondfactor is a change in the electronic properties of the material when thematerial is very small in size. At extremely small sizes quantumconfinement causes the material's band gap to gradually increase as thesize of the particles decrease. This effect is a consequence of theconfinement of an ‘electron in a box’ giving rise to discrete energylevels similar to those observed in atoms and molecule rather than acontinuous band as observed in the corresponding bulk semiconductormaterial. Thus, the “electron and hole” produced by the absorption ofelectromagnetic radiation are closer together than they would be in thecorresponding macrocrystalline material. This leads to a narrowbandwidth emission that depends upon the particle size and compositionof the nanoparticle material. QDs therefore have higher kinetic energythan the corresponding macrocrystalline material and consequently thefirst excitonic transition (band gap) increases in energy withdecreasing particle diameter.

QD nanoparticles of a single semiconductor material tend to haverelatively low quantum efficiencies due to electron-hole recombinationoccurring at defects and dangling bonds situated on the nanoparticlesurface, which may lead to non-radiative electron-hole recombinations.One method to eliminate such defects and dangling bonds on the inorganicsurface of the QD is to grow a second inorganic material, having a widerband-gap and small lattice mismatch to that of the core material,epitaxially on the surface of the core particle, producing a“core-shell” particle. Core-shell particles separate any carriersconfined in the core from surface states that would otherwise act asnonradiative recombination centers. One example is QDs having a ZnSshell grown on the surface of a CdSe core.

Rudimentary QD-based light-emitting devices have been made by embeddingcolloidally produced QDs in an optically clear LED encapsulation medium,typically a silicone or an acrylate, which is then placed on top of asolid-state LED. The use of QDs potentially has some significantadvantages over the use of the more conventional phosphors, such as theability to tune the emission wavelength, strong absorption properties,improved color rendering, and low scattering.

For the commercial application of QDs in next-generation light-emittingdevices, the QDs are preferably incorporated into the LED encapsulatingmaterial while remaining as fully mono-dispersed as possible and withoutsignificant loss of quantum efficiency. The methods developed to dateare problematic, not least because of the nature of current LEDencapsulants. QDs can agglomerate when formulated into current LEDencapsulants, thereby reducing the optical performance of the QDs.Moreover, once the QDs are incorporated into the LED encapsulant, oxygencan migrate through the encapsulant to the surfaces of the QDs, whichcan lead to photo-oxidation and, as a result, a drop in quantum yield(QY).

One way of addressing the problem of oxygen migration to the QDs hasbeen to incorporate the QDs into a medium with low oxygen permeabilityto form “beads” of such a material containing QDs dispersed within thebead. The QD-containing beads can then be dispersed within an LEDencapsulant. Examples of such systems are described in U.S. patentapplication Ser. No. 12/888,982, filed Sep. 23, 2010 (Pub. No.:2011/0068322) and Ser. No. 12/622,012, filed Nov. 19, 2009 (Pub. No.:2010/0123155), the entire contents of which are incorporated herein byreference.

Films containing QDs are described herein. FIG. 1 illustrates a priorart embodiment 100, wherein a QD-containing film 101 is disposed on atransparent substrate 102. Such a film can be useful, for example, todown-convert primary light 103 from a primary light source 104 byabsorbing primary light 103 and emitting secondary light 105. A portion106 of primary light may also be transmitted through the film andsubstrate so that the total light emanating from the film and substrateis a mixture of the primary and secondary light.

QD-containing films, such as film 101 in FIG. 1 , may be formed bydispersing QDs in a polymer resin material and forming films of thematerial using generally any method of preparing polymer films known inthe art. It has been found that QDs are generally more compatible withhydrophobic resins, such as acrylates, compared to more hydrophilicresins, such as epoxies. Thus, polymer films made of QDs dispersed inacrylates tend to have higher initial quantum yields (QYs) than QD filmsusing hydrophilic resins such as epoxy resins. However, acrylates tendto be permeable to oxygen, while epoxy resin polymers and similarhydrophilic polymers tend to be better at excluding oxygen.

One alternative for achieving high QY associated with QD-containinghydrophobic films, while also maintaining stability of the QY over time,is to insulate the film from oxygen by sandwiching the film between gasbarrier sheets, as illustrated in FIG. 2 . FIG. 2 illustrates a panel200 having a polymer film 201 contained between gas barrier sheets 202and 203. The polymer film 201 contains QDs dispersed throughout. Gasbarrier sheets 202 and 203 serve to prevent oxygen from contacting thedispersed QDs. However, even in an embodiment as illustrated in FIG. 2 ,oxygen can permeate into the film at edges 204, resulting in adeterioration of the QY of the film.

One solution to this problem is to seal edges 204 with an oxygenbarrier. However, doing so adds cost to the production of panel 200.Another option is to use a polymer 201 that is less permeable to oxygen.But as explained above, QDs are generally less compatible with suchpolymer resins, and therefore the optical properties of devicesutilizing such polymers are less than ideal.

Multi-phase films utilizing at least a first phase (phase 1) resin thatis compatible with the QD material and at least a second phase (phase 2)resin that is efficient at rejecting O₂ are described herein. FIG. 3illustrates a plan view of such a film 300, wherein QDs 301 aredispersed in a first polymer phase 302, which is typically a hydrophobicmaterial such as an acrylate resin. Regions of the first polymer phaseare dispersed throughout a second polymer phase 303, which is typicallyan oxygen-impermeable material such as epoxy.

The multi-phase films described herein overcome many of the problemsdescribed above. The phase 1 resin is compatible with the QDs andtherefore allows a high initial QY. The phase 2 resin is impermeable tooxygen, and therefore protects the QDs from oxidation without the needto seal the edges of the panel. As used herein, the term “film”includes, not only 2-dimensional (i.e. flat) sheets, as illustrated inFIGS. 1-3 , but can also include 3-dimensional shapes throughout. Gasbarrier sheets 202 and 203 serve to prevent oxygen from contacting thedispersed QDs. However, even in an embodiment as illustrated in FIG. 2 ,oxygen can permeate into the film at edges 204, resulting in adeterioration of the QY of the film.

FIG. 4 is a flowchart illustrating steps of a method of preparingmulti-phase films as described herein. The QDs are dispersed in asolution of the phase 1 resin (or resin monomer) 401. As describedabove, the phase 1 resin is generally a hydrophobic resin, such asacrylate resins. Examples of suitable phase 1 resins include,poly(methyl (meth)acrylate), poly(ethyl (meth)acrylate), poly(n-propyl(meth)acrylate), poly(butyl (meth)acrylate), poly(n-pentyl(meth)acrylate), poly(n-hexyl (meth)acrylate), poly(cyclohexyl(meth)acrylate), poly(2-ethyl hexyl (meth)acrylate), poly(octyl(meth)acrylate), poly(isooctyl (meth)acrylate), poly(n-decyl(meth)acrylate), poly(isodecyl (meth)acrylate),poly(lauryl(meth)acrylate), poly(hexadecyl (meth)acrylate),poly(octadecyl (meth)acrylate), poly(isobornyl (meth)acrylate),poly(isobutylene), polystyrene, poly(divinyl benzene), polyvinylacetate, polyisoprene, polycarbonate, polyacrylonitrile, hydrophobiccellulose based polymers like ethyl cellulose, silicone resins,poly(dimethyl siloxane), poly(vinyl ethers), polyesters or anyhydrophobic host material such as wax, paraffin, vegetable oil, fattyacids and fatty acid esters.

Generally, the phase 1 resin can be any resin that is compatible withthe QDs. The phase 1 resin may or may not be cross-linked orcross-linkable. The phase 1 resin may be a curable resin, for example,curable using UV light. In addition to the QDs and phase 1 resin (orresin monomer), the solution of 401 may further include one or more of aphotoinitiator, a cross-linking agent, a polymerization catalyst, arefractive index modifier (either inorganic one such as ZnSnanoparticles or organic one such as high refractive index monomers orpoly(propylene sulfide)), a filler such as fumed silica, a scatteringagent such as barium sulfate, a viscosity modifier, a surfactant oremulsifying agent, or the like.

The QD-phase 1 resin dispersion can then be mixed with a solution of thephase 2 resin (or resin monomer) 402. As explained above, the phase 2resin is a better oxygen barrier than the phase 1 resin. The phase 2resin is generally a hydrophilic resin. The phase 2 resin may or may notbe cross-linkable. The phase 2 resin may be a curable resin, forexample, curable using UV light. Examples of phase 2 resins includeepoxy-based resins, polyurethanes-based resins, hydrophilic(meth)acrylate polymers, polyvinyl alcohol, poly(ethylene-co-vinylalcohol), polyvinyl dichloride, silicones, polyimides, polyesters,polyvinyls, polyamides, enphenolics, cyanoacrylates, gelatin, waterglass (sodium silicate), PVP (Kollidon). The solution of phase 2 resinmay also include one or more of a photoinitiator, a cross-linking agent,a polymerization catalyst, a surfactant or emulsifying agent, or thelike.

According to some embodiments, the phase 1-phase 2 mixture forms anemulsion 403, typically and emulsion of phase 1 resin suspended in phase2 resin. The emulsion composition can be adjusted by adjusting therelative concentrations of phase 1 and phase 2 resins, the rate ofstirring of the mixture, the relative hydrophobicity of the resins, andthe like. One or more emulsifying agents, surfactants, or othercompounds useful for supporting stable emulsions may be used.

According to certain embodiments, such as the embodiment illustrated inFIG. 2 , the resin mixture is laminated between gas barrier films 404.Examples of gas barrier films include FTB3-50 (available from 3M, St.Paul, MN) and GX50W or GX25W (available from Toppan Printing Co., LT,Japan). Upon curing 405, the laminated resin film yields a polymer filmhaving regions of phase 1 polymer, containing QDs, dispersed throughoutphase 2 polymer, as illustrated in FIG. 3 .

Examples

Example 1A: Green InP/ZnS QDs (120 Optical Density (OD)) were preparedas described in U.S. patent application Ser. No. 13/624,632, filed Sep.23, 2011, the entire contents of which are incorporated herein byreference. The QDs were added to a degassed vial, the tolueneevaporated, and the resultant solid QD re-dispersed in degassed laurylmethacrylate (LMA, 2.64 mL) containing IRG819/IRG651 (Igracure®)photoinitiators (9/18 mg). Trimethylolpropane trimethacrylate (TMPTM)crosslinker (0.32 mL) was added. The mixture was further stirred for 30min under nitrogen affording phase 1 resin. Films of QDs in phase 1resin were laminated between 3M gas barrier layers on an area limited bya 19 mm×14 mm×0.051 mm plastic spacer. The film was cured with a Mercurylamp for 1 min. Stability testing of the QY of the QDs in phase 1 resinis represented by square data points in the plot illustrated in FIG. 5 .

Example 1B: Two-phase resin was prepared by mixing 148 microliters ofthe phase 1 resin with 0.5 mL degassed epoxy (Epotek, OG142) and themixture was mechanically stirred for 3 min at 100 rpm under nitrogen. 60Microliters of the two-phase resin was then laminated between 3M gasbarrier layers on an area limited by a 19 mm×14 mm×0.051 mm plasticspacer. The film was cured with a Mercury lamp for 1 min. Stabilitytesting of the QY of the QDs in two-phase resin comprising acrylate(phase 1) and epoxy (Epotek OG142, phase 2) is represented bydiamond-shaped data points in the plot illustrated in FIG. 5 .

Example 2: Green InP/ZnS QDs (120 Optical Density (OD)) were prepared asdescribed in U.S. patent application Ser. No. 13/624,632, filed Sep. 23,2011. The QDs were added to a degassed vial and dispersed in degassedlauryl methacrylate (LMA, 2.64 mL) containing IRG819/IRG651photoinitiators (9/18 mg). TMPTM crosslinker (0.32 mL) was added. Themixture was further stirred for 30 min under nitrogen affording phase 1resin. Two-phase resin was prepared by mixing 148 microliters of thephase 1 resin with 0.5 mL degassed polyurethane acrylate (DymaxOP4-4-26032) and the mixture was mechanically stirred for 3 min at 100rpm under nitrogen. 60 Microliters of the two-phase resin was thenlaminated between 3M gas barrier layers on an area limited by a 19 mm×14mm×0.051 mm plastic spacer. The film was cured with a Mercury lamp for1-5 min. Stability testing of the QY of the QDs in two-phase resincomprising acrylate (phase 1) and polyurethane acrylate (DymaxOP-4-26032, phase 2) is represented by triangle-shaped data points inthe plot illustrated in FIG. 5 .

Example 3: Green InP/ZnS QDs (120 Optical Density (OD)) were prepared asdescribed in U.S. patent application Ser. No. 13/624,632, filed Sep. 23,2011. The QDs were re-dispersed in degassed lauryl methacrylate (LMA,1.2 mL) by stirring under nitrogen overnight. IRG819 photoinitiator (3mg) was dissolved in 0.6 mL of the QD dispersion in LMA. TMPTMcrosslinker (0.073 mL) was then added. The mixture was further stirredfor 30 min under nitrogen, affording phase 1 resin with QD concentrationat 89.2 OD/mL. Two-phase resin was obtained by mixing 67 microliters ofphase 1 resin with 0.43 mL degassed epoxy (Epotek, OG142), upon whichthe mixture was mechanically stirred for 3 min at 100 rpm undernitrogen. 60 Microliters of the two-phase resin was then laminatedbetween 3M gas barrier layers on an area limited by a 19 mm×14 mm×0.051mm plastic spacer. The films were cured with a Mercury lamp for 1 min.

Example 4: Green InP/ZnS QDs (120 Optical Density (OD)) were prepared asdescribed in U.S. patent application Ser. No. 13/624,632, filed Sep. 23,2011. The QDs were dispersed in degassed lauryl methacrylate (LMA, 2.64mL) containing IRG819/IRG651 photoinitiators (9/18 mg) by stirring undernitrogen overnight. TMPTM crosslinker (0.32 mL) was added. The mixturewas further stirred for 30 min under nitrogen affording phase 1 resin.Non-crosslinkable, non-viscous acrylate phase 2 resin was prepared bydissolving 10.1 mg IRG819 in deoxygenated glycidyl methacrylate (GMA, 1mL). Non-crosslinkable, viscous acrylate phase 2 resin was prepared bydissolving polyvinylidene chloride (PVDC, Saran F310, 1.5 g) indeoxygenated GMA/IRG819/IRG651 (8.5 mL/57.5 mg/115.3 mg) solution.Two-phase resin was obtained by mixing 148 microliters of the phase 1resin with 0.5 mL degassed phase 2 resin and the mixture wasmechanically stirred for 3 min at 100 rpm under nitrogen. 60 microlitersof the two-phase resin was then either added to the well of a 19 mm×14mm glass plate or laminated between 3M gas barrier layers on an arealimited by a 19 mm×14 mm×0.051 mm plastic spacer. The film was finallycured with Mercury lamp for 5 min.

Stability of Resin Films

FIG. 5 is a plot illustrating the quantum yield of resin films of QDsupon exposure to a blue backlight unit (BLU) for amounts of time (time,in days, denoted on the x-axis). The QY of green QDs in a single-phaseLMA resin, as prepared in Example 1a above, is represented by squaredata points 501. The single-phase resin film has an initial QY of about60%, but the QY drops substantially during the first week of exposure.

Diamond-shaped data points 502 represent the QY of a two-phase film ofLMA/epoxy resin containing QDs prepared as describe in Example 1b above.The initial QY of the LMA/epoxy two-phase film is also about 60%, butunlike that of the single-phase film, the QY of the two-phase filmremains constant over the time period of the experiment. The stabilityof the QY indicates that the two-phase film effectively preventsoxidation of the QDs.

Triangle-shaped data points 503 represent QY a two-phase film of QDs inLMA/polyurethane acrylate, as prepared in Example 2 above. The initialQY of the LMA/polyurethane acrylate film is about 45% and remains stablefor over three months. FIG. 6 illustrates stability studies of thetwo-phase LMA/epoxy film prepared in Example 1b. LED intensity 601,efficacy 602, photoluminescence intensity 603, QD/LED ratio 604, and %EQE 605 remain stable and above T70 606 for at least 2000 hours.

Effect of Refractive Index of Phase 2 Resin

The phase 1 LMA resin used in the above Examples has a refractive index(RI) of 1.47. Table 1 illustrates the effect of the RI of the phase 2resin effects the optical properties of the two-phase films.

Effect of Refractive Index of Phase 2 Resin (RI of Phase 1 Resin=1.47).

RI of cured Initial Initial Phase 2 Phase 2 2-phase 2-phase Sample QYEQE Resin Resin QY EQE 1 60 69 Urethane 1.47 60 72 acrylate (OP4-4-20639) 2 60 69 Urethane 1.55 54 59 acrylate (Dymax OP4-4- 26032) 3 60 69Epoxy 1.58 59 58 (Epotek- OG142

As shown in Table 1, when the RI of the first phase and that of thesecond phase are matched, the initial QY and EQE of the film ismaximized. When there is mismatch between the RIs of the first andsecond phase resins, the initial QY and EQE of the film is reduced.Thus, it is beneficial, where possible, to use first and second phaseresins that have closely matched RIs. According to some embodiments, theRIs of the two resins differ by less than about 5%. According to someembodiments, the RIs of the two resins differ by less than about 1%.

Accordingly, additives such as surfactants, viscosity modifiers,monomers, light scattering agents, and other inorganic surface tensionmodifiers may be used to adjust the RI of one or both phases so that theRIs match. Such additives may also be used to minimize chemicalinteraction between the phases. Moreover, chemical antioxidants(dilaurylthiodipropionate, octadecylsulfide, octadecanethiol,cholesteryl palmitate, Zinvisible, ascorbic acid palmitate, alphatocopherol, BHA, BHT, octane thiol, lipoic acid, gluthathione, sodiummetabisulfite, trioctyl phosphine (TOP), tetradecylphosphonic acids,polyphenols) may be added to one or both phases to minimize thedegradation of QDs around the edges of the two-phase/gas barrierencapsulated QD films.

The inventive concepts set forth herein are not limited in theirapplication to the construction details or component arrangements setforth in the above description or illustrated in the drawings. It shouldbe understood that the phraseology and terminology employed herein aremerely for descriptive purposes and should not be considered limiting.It should further be understood that any one of the described featuresmay be used separately or in combination with other features. Otherinvented systems, methods, features, and advantages will be or becomeapparent to one with skill in the art upon examining the drawings andthe detailed description herein. It is intended that all such additionalsystems, methods, features, and advantages be protected by theaccompanying claims.

What is claimed is:
 1. A light emitting device comprising: a primarylight source; and a panel comprising a quantum dot (QD)-containingcomposition disposed between gas barrier sheets, wherein theQD-containing composition is a cured emulsion having a plurality ofdomains of a first resin contained within a continuous domain of asecond resin, and quantum dots are dispersed in the first resin.
 2. Thelight emitting device of claim 1, wherein the primary light source is abacklight unit (BLU).
 3. The light emitting device of claim 1, whereinthe first resin is selected from the group consisting of apoly(methyl(meth)acrylate), a poly(ethyl(meth)acrylate), apoly(n-propyl(meth)acrylate), a poly(butyl(meth)acrylate), apoly(n-pentyl(meth)acrylate), a poly(n-hexyl(meth)acrylate), apoly(cyclohexyl(meth)acrylate), a poly(2-ethyl hexyl(meth)acrylate), apoly(octyl(meth)acrylate), a poly(isooctyl(meth)acrylate), apoly(n-decyl(meth)acrylate), a poly(isodecyl(meth)acrylate), apoly(lauryl(meth)acrylate), a poly(hexadecyl(meth)acrylate), apoly(octadecyl(meth)acrylate), a poly(isobornyl(meth)acrylate), apoly(isobutylene), a polystyrene, a poly(divinyl benzene), a polyvinylacetate, a polyisoprene, a polycarbonate, a polyacrylonitrile, ahydrophobic cellulose based polymer, a silicone resin, a poly(dimethylsiloxane), a poly(vinyl ether), and a polyester.
 4. The light emittingdevice of claim 3, wherein the first resin is apoly(lauryl(meth)acrylate).
 5. The light emitting device of claim 1,wherein the second resin is selected from the group consisting of anepoxy-based resin, a polyurethane-based resin, a hydrophilic(meth)acrylate, a polyvinyl alcohol, a poly(ethylene-co-vinyl alcohol),a polyvinyl dichloride, a silicone, a polyimide, a polyester, apolyvinyl, a polyamide, an enphenolic, a cyanoacrylate, gelatin, asodium silicate, and poly(vinylpyrrolidone) (PVP).
 6. The light emittingdevice of claim 5, wherein the second resin is an epoxy-based resin, apolyurethane-based resin.
 7. The light emitting device of claim 6,wherein the polyurethane-based resin is a polyurethane acrylate resin.8. The light emitting device of claim 6, wherein the first resin is apoly(lauryl(meth)acrylate).
 9. The light emitting device of claim 1,wherein the quantum dots are InP/ZnS quantum dots.
 10. The lightemitting device of claim 1, wherein at least one of the first resin andthe second resin further comprises a light scattering agent dispersedtherein.
 11. The light emitting device of claim 1, wherein at least oneof the first resin and the second resin further comprises a chemicalantioxidant dispersed therein.
 12. The light emitting device of claim 1,wherein a refractive index of the first resin and a refractive index ofthe second resin differ by less than about 5%.
 13. The light emittingdevice of claim 12, wherein the refractive index of the first resin andthe refractive index of the second resin differ by less than about 5%.14. The light emitting device of claim 1, wherein the first resinfurther comprises a refractive index modifier dispersed therein.